African American men experience health disparities across a number of preventable chronic diseases, including cardiovascular disease, strokes, obesity, and diabetes. Physical activity (PA) is a modifiable risk factor for these conditions. The few PA promotion studies that have included African American men have resulted in successful short-term behavior change, yet in order for the health benefits of PA to be realized, PA levels must be maintained. While behavior change maintenance programs have been shown to assist participants in sustaining behavior change, we were unable to identify any studies that have developed maintenance programs specifically targeting African American men. The purpose of this proposal is to develop a PA maintenance program for African American men. This Phase I STTR project, MobileMen, will deliver the intervention utilizing mHealth technology and therefore, will be led by researchers and multimedia developers at Klein Buendel, Inc. (KB) and Pennington Biomedical Research Center (Dr. Newton, PI). The use of mHealth, as opposed to other avenues of intervention delivery, is based on published reports documenting that African Americans perceive mobile technology as an acceptable means of intervention delivery. In addition, ownership of smartphones and the use of text messaging are highest among African Americans compared to other ethnic groups. There is a need to tailor this intervention towards African American men because they have unique gender role beliefs which influence exercise promotion. There is also increasing recognition of the need for researchers to develop interventions in collaboration with the target population. Therefore, the current proposal will involve conducting formative research with African American men to identify the key elements for program development. The fact that mHealth is acceptable to- and the fact that the application will be developed in collaboration with African American men, leads us to hypothesize that African American men will view the mHealth intervention as acceptable, feasible, and usable. In this Phase I STTR, we will: (1) conduct multi-method formative research to guide app design and content, (2) produce a functioning app prototype, and (3) conduct usability testing on the prototype for functionality, ease of use, and interest among African American men. To our knowledge, no study has utilized mobile phones as a means of effecting PA levels in African American men. MobileMen will address an unmet need in the marketplace as it will be the first smartphone app that is targeted toward PA maintenance in African American men.